Department of Applied Physics, Graduate School of Engineering , Nagoya University , Nagoya 464-8603 , Japan.
Department of Chemistry, Graduate School of Science , Kyoto University , Kyoto 606-8502 , Japan.
Inorg Chem. 2019 Nov 4;58(21):14304-14315. doi: 10.1021/acs.inorgchem.9b00186. Epub 2019 Apr 9.
Anomalous successive structural transitions in layered 1-CrSe with an unusual Cr valency were investigated by synchrotron X-ray diffraction. 1-CrSe exhibits dramatic structural changes in in-plane Cr-Cr and interlayer Se-Se distances, which originate from two interactions: (i) in-plane Cr-Cr interactions derived from Peierls-like trimerization instabilities on the orbitally assisted one-dimensional chains and (ii) interlayer Se-Se interactions through p-p hybridization. As a result, 1-CrSe has the unexpected ground state of an antiferromagnetic metal with multiple Cr linear trimers with three-center-two-electron σ bonds. Interestingly, partial substitution of Se for S atoms in 1-CrSe changes the ground state from an antiferromagnetic metal to an insulator without long-range magnetic ordering, which is due to the weakening of interlayer interactions between anions. The unique low-temperature structures and electronic states of this system are determined by the competition and cooperation of in-plane Cr-Cr and interlayer Se-Se interactions.
通过同步辐射 X 射线衍射研究了具有不寻常 Cr 价态的层状 1-CrSe 中异常的连续结构转变。1-CrSe 在面内 Cr-Cr 和层间 Se-Se 距离上表现出剧烈的结构变化，这源于两种相互作用：（i）来自轨道辅助一维链上的类 Peierls 三聚体化不稳定性的面内 Cr-Cr 相互作用，以及（ii）通过 p-p 杂化的层间 Se-Se 相互作用。结果，1-CrSe 具有意想不到的基态，即具有三个中心两个电子 σ 键的多个 Cr 线性三聚体的反铁磁金属。有趣的是，在 1-CrSe 中部分取代 Se 原子会使基态从反铁磁金属变为无长程磁有序的绝缘体，这是由于阴离子层间相互作用的减弱。该体系的独特低温结构和电子态由面内 Cr-Cr 和层间 Se-Se 相互作用的竞争和协同决定。
